1.8 Adolescent parity progression ratios
Adolescent parity progression ratios measure the proportion of all women who initiate childbearing before turning 20, the conditional proportion of adolescents with one birth who have a second before turning 20 (that is, the ratio with one birth who go on to have a second in adolescence), and so forth. While progression ratios are complex, there are aspects of them, particularly when disaggregated into age groups of first birth, that are valuable for lay audiences. For example, the ratios clarify what proportion of women begin childbearing in adolescence, and at what adolescent ages, which is important for highlighting trends and vulnerabilities among the youngest. For more technical reporting, the progression ratios are powerful for detailing parity-specific trends in countries, which are particularly relevant for improving the targeting of interventions. Ratios provide important information that proportions do not. For example, in a country with a decline in first births in adolescence, the proportion of women with a second birth must also necessarily decline. However, this does not necessarily mean that the incidence of second adolescent births is declining among those at risk of having a second adolescent birth. Only the progression ratio can clarify whether those at risk of a second adolescent birth (that is, all adolescents with a first birth) are more or less likely to have a second birth compared to women in the past. The analysis will produce country-specific, regional and global trends.
These progression ratios are also powerful when accompanied by figures and discussions about age and rapid repeat birth dynamics in country-specific analysis. For example, Ghana’s total adolescent fertility has seen encouraging decline, but its progression ratios at parities 3 and 4 have changed very little, suggesting that there is a core group of exceptionally vulnerable girls (those who start at the youngest ages) that have been left behind. In contrast, Burkina Faso has seen relatively good progress in declines at parities two and above and has comparatively few rapid repeat births. However, first birth rates have been fairly stagnant. Their greatest gains would be in focusing on reducing first births. If declines in first births were to fall in tandem with declines at other parities in the country, it would see much more rapid and impressive declines in total adolescent fertility than what has occurred to date. In Benin, like Ghana, there needs to be a focus on the youngest starters who have several adolescent births in quick succession. Each country’s combination of age, parity and inter-birth interval dynamics are unique and highly informative.